Process for continuous manufacture of rigid corrugated cardboard with crossed corrugations



May 19, 1970 R. CARREL 5 9 PROCESS FOR CONTINUOUS MANUFACTURE OF RIGID CORRUGATED ATIONS CARDBOARD WITH CROSSED CORRUG 2 Sheets-Sheet 1 Filed July 28, 1967 RENE CARREL a May 19, 1970 R. CARREL 3,513,054

PROCESS FOR CONTINUOUS MANUFACTURE OF RIGID CORRUGATED CARDBOARD WITH CROSSED CORRUGATIONS Filed July 28. 1967 2 Sheets-Sheet 2 JNVEIVI'OE RENE CARREL ZZ W Wow A TIDE/KEYS United States Patent Int. Cl. imr 1/22 US. Cl. 156-292 2 Claims ABSTRACT OF THE DISCLOSURE A process for continuous manufacture of rigid corrugated cardboard with crossed corrugations, characterised in that two webs of corrugated cardboard with oblique corrugations are made, each by passages of a cardboard web between two co-operating corrugating cylinders wtih helical grooving, this web being introduced between these two cylinders in a direction forming with the generatrices of the two cylinders a given angle such that deformation of the web in the grooves in the cylinders imposes on the corrugated web a movement in a direction perpendicular to these generatrices, and the two corrugated webs are each provided with a covering web before they are joined by gluing the crests of the oblique corrugations which cross each other. Apparatus for carrying out this process.

The invention relates to a process and apparatus for continuous manufacture of rigid corrugated cardboard, with crossed corrugations, i.e. with corrugations running obliquely relative to each other.

Sheets or panels of rigid corrugated cardboard have previously been made by gluing together two webs of corrugated cardboard with ordinary corrugations, i.e. corrugations perpendicular to the edges of the webs, and making the corrugations in the two webs cross over each other. The resulting sheets or panels have the same bending resistance, whatever the direction of bending.

To this end, it has been proposed that ordinary corrugated cardboard webs with at least one covering sheet should be cut in a direction oblique relative to the corrugations, and that the two cut elements should be stuck together with their corrugations crossing. This method involves much wastage, and the sheets or panels with crossed corrugations are necessarily restricted in width and length.

It has also been proposed that corrugated cardboard webs with corrugations oblique relatively to the web edges should be made directly, so that panels with crossed undulations can be made by superimposing and gluing the two webs.

Continuous production of webs with oblique corrugations has met with difficulties, mainly because the paper web has followed a lateral path relative to the grooved elements for making the corrugations.

Various'solutions have been proposed, more particularly pairs of cylinders with helical grooves, or a cylinder with straight grooves cooperating with corresponding grooves in a movable rectilinear element, the cylinder axis forming an angle with the direction of movement of the rectilinear element, or pairs of cylinders with oblique grooves whose ribs are movable parallel to each other.

The solutions proposed have not been popular in practice, and insofar as they could give corrugated cardboard webs with oblique corrugations, these webs would 'ice be limited in length since the webs cannot be stored in roll form.

The invention permits continuous manufacture of sheets or panels of corrugated cardboard with crossed corrugations, of any length.

In accordance with the invention, two webs of corrugated cardboard with oblique corrugations are made, each by passage of a cardboard web between two cooperating corrugating cylinders with helical grooving, this web being introduced between these two cylinders in a direction forming with the generatrices of the two cylinders a given angle such that deformation of the web in the grooves in the cylinders imposes on the corrugated web a movement in a direction perpendicular to these generatrices, and the two corrugated webs are each provided with a covering web before they are joined by gluing the free crests of the oblique corrugations which cross each other.

The invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a diagram illustrating the deformation of a cardboard web in the grooves in cylinders;

FIGS. 2 and 3 are diagrammatic elevation and p an views respectively of a cardboard web during corrugation;

FIG. 4 is a diagrammatic elevation illustrating the formation of cardboard 'with two thicknesses of corrugated cardboard and with crossed corrugations; and

FIGS. 5 and 6 are plan views illustrating the formation of each of the two webs for constituting the cardboard with crossed corrugations.

In the developed diagram in FIG. 1, the straight line x-x designates a generatrix of a corrugating cylinder with helical grooving. The straight line y-y, which corresponds to the crest of a rib in the helical grooving, forms with the generatrix x-x an angle at which will be the angle of inclination of the corrugations in a web of cardboard. A point A on the web of cardboard will be entrained, during rotation of the cylinder, in a plane z-z perpendicular to the generatrix xx.

According to one of the features of the invention, the cardboard web is brought to the corrugating cylinder at a predetermined angle 5 to the plane z-z.

The value of the angle 6 is determined as follows.

A point B on a cardboard web, tangent to a smooth corrugating cylinder whose diameter corresponds to the crests of the ribs in the grooving, would be entrained in a plane z'z' parallel to the plane z-z by rotation of the cylinder. If L is the developed length of a groove, following a direction perpendicular to yy, and if a is the pitch of the groove, an angle 5 can be determined such that, for a shift b=La of the point B caused by the section of the groove, this point reaches B in the plane zz passing through the point A, i.e. in a plane perpendicular to the cylinder axis. The diagram in FIG. 1 shows that the angle ,8 depends both on the angle of inclination a of the grooves and on the section and pitch of the grooves.

For rotation of the corrugating cylinder corresponding to the apparent pitch of the helical grooves, the point A moves in the plane zz till it reaches A and the point B reaches A, due to the combined effect of the rotation of the cylinder and the deformation of the cardboard web in the groove on the cylinder. Consequently, the web of corrugated cardboard will be entrained along a direction perpendicular to the cylinder axis.

The relative forward movement of the cardboard web towards the cylinder is accompanied by a movement in translation of the web, parallel to the fianks of the grooves. For each point on the web B the value of this translatory movement will be equal to the distance B'C. Stressing of the cardboard on account of this translatory movement will be slight, since the zone of corrugating under pressure in each groove will be less than one-third of the total zone of deformation of the web for a groove, i.e. the translation under pressure will be limited to B'C/3.

FIG. 2 shows two cooperating corrugating cylinders 1, 2 between which a smooth cardboard web 3 engages along a plane perpendicular to the plane passing through the axes of the two cylinders. The corrugated cardboard runs around the lower cylinder 1. Upstream of the two cylinders the smooth cardboard web is guided on at least one smooth cylinder 4 whose axis is inclined, relative to the axes of the two corrugating cylinders, by the angle [3 determined as indicated in the diagram in FIG. 1.

FIG. 3, which omits the upper cylinder 2, shows the web 3 forming at a point the angle 5 plus 90 with the line of engagement E with the crests of the ribs in the grooving on the two cylinders. The origin of deformation of the cardboard web, for each corrugation, is therefore at the point 0 on the line B, and deformation advances along the line B. Conseqeuntly, downstream of the line E, each corrugation in the web must wind helically round the cylinder 1. To this end, a guide piece 5 is arranged around the cylinder 1, allowing passage of the upper cylinder 2 and having two projections 5a extending beyond the line of engagement E. The curvature imposed on the corrugations by their helical winding will depend on the angle of inclination of the helix and the diameter of the corrugating cylinders. It will remain slight, and, by selection of this angle and diameter, can be limited to a value compatible with flexibility of the cardboard before drying.

The helical winding of the corrugations means that the corrugated web can leave the cylinder 1 in the form of a web 3' with oblique corrugations.

This web cannot be stored in roll form.

In accordance with the invention, the webs with oblique corrugations made as described above are used directly for making sheets or panels of any length, with crossed corrugations, in apparatus supplied with smooth cardboard webs.

This apparatus is shown diagrammatically in elevation in FIG. 4.

A smooth cardboard web 3a, unwinding 011 a roll 6a and guided by oblique rolls 4a is corrugated as it passes through corrugating cylinders 2a, 1a, with helical grooving. Similarly, a smooth cardboard web 3b, unwinding from a roll 6b and guided by oblique rolls 4b, is corrugated as it passes between corrugating cylinders 2b and 1b.

Two gluing cylinders 7a, 7b, cooperating with the cylinders 1a, 1b, deposit glue on the crests of the corrugations.

A smooth cardboard web 80, winding oif a roll 9a and guided by a roll a, is pressed by a cylinder 11a onto the glued web 3' as it leaves the corrugating cylinder 1a. Similarly, a smooth cardboard 8b, winding off a roll 9b and guided by a roll 10b, is pressed by a cylinder 11b onto the glued web 3b.

The smooth webs 8a, 8b move in a direction perpendicular to the plane X-X passing through the corrugating cylinders 1a, 2a and 1b, 2b, and the smooth webs 3a, 3b move in a direction inclined at the angle 5 to this plane.

When they leave the corrugating cylinders 1a, 2a and 1b, 2b, the webs 3a and 3b, respectively glued to the smooth webs 8a and 8b, move in a direction perpendicular to the plane XX, and are glued by gluing cylinders 12a and 13b before they pass between pressure cylinders 13 to form a composite web 30 in which the corrugations cross-i.e., run obliquely relative to each otherand are glued together where they cross, both faces of this composite web being covered by the smooth webs 8a, 8b. The composite web 3c passes between two guide cylinders 14 and can then be cut with any type of cutter (not shown) into sheets or panels of the desired length, which are easy to store in stacks.

It is therefore possible to produce continuously, from four rolls of smooth cardboard, sheets or panels of cardboard with crossed corrugations, with high bending resistance whatever the bending angle.

Obviously, the embodiment described above may be modified or added to without exceeding the scope of the invention.

Thus, more particularly, the orientation of the guide rolls for the cardboard webs awaiting corrugation, i.e. upstream of the corrugating cylinders, may be adjustable according to the pitch of the grooves and according to the thickness and nature of the cardboard used. This adjustment may be adapted to each individual case, or, by means of a device for detecting any deviation, it may be made continuously dependent on correct winding of the web.

What is claimed is:

1. A process for continuous manufacture of rigid corrugated cardboard with crossed corrugations running obliquely relative to each other, the steps of forming two webs of corrugated cardboard with oblique corrugations by passage of two cardboard webs each between two cooperating corrugating cylinders with helical grooving in a direction forming with the generatrices of the two cylinders a given angle such that deformation of the web in the grooves in the cylinders imposes on the corrugated web a movement in a direction perpendicular to these generatrices, then securing a covering web on each of the two corrugated webs and then joining the two corrugated webs by gluing the free crests of the oblique corrugations thereof which cross each other.

2. Apparatus for continuous manufacture of rigid corrugated cardboard with crossed corrugations, comprising two identical units for forming two cardboard webs with oblique corrugations, each unit having a pair of cooperating corrugating cylinders with helical grooves, at least one oblique guide roll for the web awaiting corrugation upstream of the corrugating cylinders, a gluing cylinder for gluing the crests of the corrugations in the cardboard wound onto one of the cylinders, a pressure cylinder for pressing onto the glued crests a smooth web unrolled in a direction perpendicular to the corrugating cylinders, and a cylinder for gluing the free crests of the corrugations in the corrugated web, the apparatus further having, downstream of the two units, a pair of cooperating cylinders for joining the two webs by the glued crests of their corrugations which cross each other.

References Cited UNITED STATES PATENTS 1,051,660 1/1913 Arnesbury 156-470 1,100,064 6/1914 Ferres 156-210 3,189,502 6/1965 Little 156-210 CARL D. QUARFORTH, Primary Examiner H. E. BEHREND, Assistant Examiner U.S. Cl. X.R. 

